U.S. patent number 5,054,962 [Application Number 07/649,244] was granted by the patent office on 1991-10-08 for process for sealing the surface of dumps.
This patent grant is currently assigned to Bayer Aktiengesellschaft. Invention is credited to Heinz Bahnmuller, Hans-Otto Fricke, Bernd Koglin, Rolf Rink, Wolfgang Vogel.
United States Patent |
5,054,962 |
Bahnmuller , et al. |
October 8, 1991 |
Process for sealing the surface of dumps
Abstract
A waste dump of a standard dump class is covered with at least
one waste layer of a lower dump class having a correspondingly
lower hazard potential. Furthermore, at least the outer waste layer
is provided with a surface-sealing system. Particularly good
encapsulation of hazardous wastes is achieved if the latter are
covered with other waste layers where the dump class decreases in
an outward direction, so that each waste layer is enclosed by a
waste layer which lies on top and is of a lower dump class. In this
way, waste dumps having a high hazard potential can be reliably
enclosed for a long time and isolated from the environment at less
expense than in the past.
Inventors: |
Bahnmuller; Heinz (Kuerten,
DE), Fricke; Hans-Otto (Lohmar, DE),
Koglin; Bernd (Bergisch-Gladbach, DE), Rink; Rolf
(Cologne, DE), Vogel; Wolfgang (Siegburg,
DE) |
Assignee: |
Bayer Aktiengesellschaft
(Leverkusen, DE)
|
Family
ID: |
6369221 |
Appl.
No.: |
07/649,244 |
Filed: |
January 31, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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441810 |
Nov 27, 1989 |
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Foreign Application Priority Data
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Dec 15, 1988 [DE] |
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3842213 |
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Current U.S.
Class: |
405/129.6;
405/129.8 |
Current CPC
Class: |
B09B
1/004 (20130101); E02D 31/004 (20130101); Y02W
30/30 (20150501) |
Current International
Class: |
B09B
1/00 (20060101); E02D 31/00 (20060101); B09B
001/00 () |
Field of
Search: |
;405/128,129,258,52,263
;252/633 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Taylor; Dennis L.
Attorney, Agent or Firm: Sprung Horn Kramer & Woods
Parent Case Text
This application is a continuation of application Ser. No. 441,810,
filed 11/27/89 now abandoned.
Claims
We claim:
1. A method for the disposal of wastes of different hazard levels,
comprising the steps of: disposing wastes of different hazard
levels selected from the group consisting of Classes 1-5 in a dump
in successive layers with graded hazard levels such that each layer
of waste is covered by a layer of waste having a lower hazard
level, by disposing a layer of special waste having a hazard level
of Class 5 or industrial waste having a hazard level of Class 4 as
a bottom layer, covering the bottom layer with a mineral seal,
encapsulating the bottom layer with at least one of a layer of
drainable building rubble, minerals resembling building rubble and
excavated soil of Classes 1 and 2 to form a top layer and surface
sealing the top layer with a mineral seal, a drainage layer and
cultivatible soil.
2. The method according to claim 1, further comprising disposing an
intermediate layer of domestic waste of Class 3 between the bottom
layer and the top layer.
3. The method according to claim 1, comprising making the waste
layers with a thickness of 1 to 30 m.
4. The method according to claim 1, comprising making the waste
layers with a thickness of 3 to 10 m.
5. The method according to claim 1, further comprising collecting
surface water which penetrates the drainable building rubble,
minerals resembling building rubble and excavated soil in a
separate channel system, analyzing the collected water for
pollutants and feeding the water for wastewater treatment depending
upon the analysis.
6. The method according to claim 1, comprising making a lower
portion of the layer of drainable building rubble, minerals
resembling building rubble and excavated soil with a thickness of
at least 0.3 m consisting of at least 95% of particle fractions of
sand, gravel and stones for drainage.
7. The method according to claim 1, further comprising laying slabs
or blocks of at least one of building rubble, minerals resembling
building rubble and excavated soil compressed under high pressure
in the form of roofing tiles or building blocks as an outer layer
of at least 0.3 m thick on the drainage layer.
8. A method for the disposal of wastes of different hazard levels,
comprising the steps of: disposing wastes of different hazard
levels selected from the group consisting of Classes 1-5 in a dump
in successive layers with graded hazard levels such that each layer
of waste is covered by a layer of waste having a lower hazard
level, by disposing a layer of special waste having a hazard level
of Class 5 as a bottom layer, covering the bottom layer with a
mineral seal, encapsulating the bottom layer with a layer of
industrial waste having a hazard level of Class 4 and a mineral
seal, covering the encapsulating layer with at least one of a layer
of drainable building rubble, minerals resembling building rubble
and excavated soil of Classes 1 and 2 to form a top layer and
surface sealing the top layer with a mineral seal, a drainage layer
and cultivatible soil.
9. The method according to claim 8, further comprising disposing an
intermediate layer of domestic waste of Class 3 between the bottom
layer and the top layer.
10. The method according to claim 8, comprising making the waste
layers with a thickness of 1 to 30 m.
11. The method according to claim 8, comprising making the waste
layers with a thickness of 3 to 10 m.
12. The method according to claim 8, further comprising collecting
surface water which penetrates the drainable building rubble,
minerals resembling building rubble and excavated soil in a
separate channel system, analyzing the collected water for
pollutants and feeding the water for wastewater treatment depending
upon the analysis.
13. The method according to claim 8, comprising making a lower
portion of the layer of drainable building rubble, minerals
resembling building rubble and excavated soil with a thickness of
at least 0.3 m consisting of at least 95% of particle fractions of
sand, gravel and stones for drainage.
14. The method according to claim 8, further comprising laying
slabs or blocks of at least one of building rubble, minerals
resembling building rubble and excavated soil compressed under high
pressure in the form of roofing tiles or building blocks as an
outer layer of at least 0.3 m thick on the drainage layer.
Description
BACKGROUND OF THE INVENTION
Sealing the surface of waste dumps is very important in terms of
environmental protection. The long-term physical and chemical
interactions of the dump with the terrain in which the dump has
been set up are critical. With regard to danger to the environment
(hazard potential), 5 different dump classes have been defined, in
the following order:
Dump class 5=Special wastes
Dump class 4=Commercial and industrial wastes
Dump class 3=Domestic wastes
Dump class 2=Building rubble
Dump class 1=Excavated earth.
In this sequence, the hazard potential decreases from top to
bottom; that is to say, the special wastes are attributed the
highest hazard potential and the excavated earth the lowest hazard
potential. To minimise migration and washing of pollutants out of
dumps, a number of regulations on sealing the surface of dumps have
recently been defined. Thus, for example for sealing the surface of
a dump for special wastes (dump class 5), the following covering
layers are prescribed from the inside outward:
A compensating layer of homogeneous, non-binding material, which is
at least 0.5 m thick, above the special waste;
over this, where there is a possibility of gas formation, a
continuous filtration-stable drainage layer at least 0.3 m thick
for gas drainage;
above this a mineral seal which is at least 0.5 m thick and has a
permeability k.ltoreq.5.times.10.sup.-10 m/s;
on top of this (as a combination seal with the mineral seal), an
HDPE plastic sheet at least 2 mm thick;
above this, a 0.3 m thick mineral drainage layer;
and, as the uppermost layer, a 1.0 m to 1.5 m thick protective and
vegetation layer such as soil which can be cultivated and
planted.
For dumps for domestic waste (dump class 3), a surface seal
comprising the following sequence of layers is specified:
Above the waste of dump class 3, a compensating layer;
above this, a gas drain which is at least 0.2 m thick and may be
provided with geotextile;
above this, a 0.5 m thick mineral seal having a permeability of
k.ltoreq.5.times.10.sup.-10 m/s;
above this, possibly a plastic sealing sheet;
above this, a drainage layer at least 0.2 m thick;
and finally once again a protective and recultivation layer.
According to a guideline for building rubble dumps, the following
requirements are set for sealing the surface of dumps for building
rubble and wastes resembling building rubble (dump class 2):
The thickness of the surface seal should not be less than 50 cm and
that of the water-removal layer (drainage layer) should not be less
than 30 cm. The permeability of the sealing layer must be
k.ltoreq.1.times.10.sup.-8 m/s and that of the drainage layer must
be k.ltoreq.1.times.10.sup.-4 m/s.
For dumps for excavated earths (dump class 1), the same draft
guideline requires no surface seals.
The surface-sealing systems for dump classes 3 to 5 according to
the present state-of-the-art, which comprise a combination seal of
a mineral seal with a plastic sheet lying directly on top, have the
following disadvantages:
The plastic sealing sheet has only limited aging resistance, only
limited resistance to microorganisms and only limited stability
through root penetration and attack by rodents;
particularly on slopes, there are still unsolved problems with
regard to the danger of the slipping of the soil layers on the
plastic sealing sheet;
because of the small root penetration depth (<2 m) unrestricted
planting is not possible. Uncontrolled growth even by deep-rooted
plants (for example trees) through natural seeding is to be
prevented;
there is no high stability against wind, particularly in the event
of incorrect growth.
In these circumstances, it can be seen that the long-term stability
and erosion resistance of the known surfacesealing systems are
unsatisfactory.
SUMMARY OF THE INVENTION
The invention is applicable here. It is the object to enclose waste
dumps having a relatively high hazard potential (relatively high
dump classes) in a better manner and more reliably for a long time
and to isolate them from the environment. The measures required for
this purpose must be economically acceptable; that is to say, any
increases in costs in the setting up of dumps must be small and
acceptable.
This object is achieved, according to the invention, if a waste
dump of a relatively high dump class (for example Classes 3 to 5)
is covered with at least one waste layer of a lower dump class
having a correspondingly lower hazard potential and if at least the
outer waste layer is provided with a surface-sealing system known
per se.
This enclosure or encapsulation process is advantageously carried
out by a procedure in which several waste layers having dump
classes decreasing in an outward direction are deposited
successively one on top of the other, so that each waste layer is
enclosed by a waste layer which lies above it and is of a lower
dump class.
A dump which has a relatively high hazard potential (relatively
high dump class) and has been sealed by this method is thus
encapsulated and protected by one or more thick layers of wastes of
lower hazard potential (lower dump classes) using the relevant
surface-sealing systems. The thickness of the individual waste
layers having dump classes decreasing in an outward direction
should be 1 to 30 m, preferably 3 to 10 m. In this way, the wastes
having a higher hazard potential are isolated from the environment
with high reliability. On the other hand, wastes having a lower
hazard potential need no longer be disposed of separately on a dump
specially set up for this purpose, since they are utilised for
sealing a dump of a higher class. This has opened up a completely
new possibility of fulfilling the basic requirement for utilising
wastes of lower dump classes.
The process according to the invention is particularly preferably
applied by a procedure in which a dump of Class 5 (special wastes),
of Class 4 (commercial and industrial wastes) or of Class 3
(domestic wastes) is covered by a layer of several meters of
building rubble (preferably .gtoreq.3 m), on which waste layers of
dump classes 3 to 5, which layers are provided with a mineral seal,
is applied, and is covered on top with a known surface seal
suitable for dumps for building rubble. In addition, the resulting
dump surface between the mineral seal for the building rubble dump
and the layer of cultivatable soil can be enriched with excavated
earth of dump class 1. For this purpose, building rubble (dump
class 2) and/or excavated earth (dump class 1) are always
advantageously applied as an outer dump layer on the dump core with
a higher class.
Advantageously, the layer of building rubble, minerals resembling
rubble and/or excavated earth is applied to a mineral sealing layer
which covers the waste layer underneath.
In a further development of the invention, the outer dump layer is
such that slabs or blocks of building rubble compressed under high
pressure or minerals resembling building rubble and/or excavated
earth are laid like roofing tiles or in the form of a wall over a
drainable rubble layer at least 0.3 m thick.
The following advantages are achieved with the invention:
The several meter thick upper dump layer of building rubble,
minerals resembling building rubble or excavated earth forms a
reliable permanent barrier against rodents and against roots.
The upper dump layer ensures high stability to erosion.
The upper dump layer provides long-lasting protection for mineral
seals underneath.
The upper dump layer can serve as a very thick drainage layer.
The upper dump layer allows any plants to be planted. Even
deep-rooted plants (trees) and uncontrolled growth through natural
seeding are permissible.
Even in the event of uncontrolled growth, there is high stability
to wind.
The dump structure permits stable slopes (high slope
stability).
The total surface-sealing system is resistant to
microorganisms.
Illustrative examples of the invention are described in detail
below with reference to drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross-section through a four-layer dump deposited in
accordance with the process according to the invention,
FIG. 2 shows a cross-section through a special wastes dump provided
with a mineral seal and encapsulated by a building rubble dump with
an associated sealing system,
FIG. 3 shows the surface drainage system of the same dump and FIG.
4 shows a corresponding multi-layer dump in which the outer
building rubble dump consists partly of slabs or blocks of
compressed, mineral material resembling building rubble and/or
excavated earth.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, a dump 2, for example a special wastes dump of Class 5,
is laid out on a base sealing system 1 and covered with a
surface-sealing system 3, for example a mineral seal with drainage.
A waste layer 4 of a lower dump class, for example Class 4, is then
applied on top of this. The waste layer 4 is in turn provided with
a surface seal 3. Further waste layers 5 and 6 where the dump
classes decrease in an outward direction, for example building
rubble (dump class 2) and, on top of this, excavated earth (dump
class 1) are then deposited on top of this. The outermost layer 6
is finally covered with a surface-sealing system 7 suitable for
outer seals. The base seal may consist of a combination of plastic
sealing sheets with mineral sealing layers. The mineral seal
usually used is a fine-grain clay material. The gradation of the
particle sizes of the mineral material must prevent discharge of
very fine constituents.
In the simplest variant of the process according to the invention,
a dump of Class 5 (special wastes), of Class 4 (commercial and
industrial wastes) or of Class 3 (domestic wastes) is provided with
a mineral seal and then covered (encapsulated) with a layer of
several meters of building rubble (preferably a coarse fraction of
prepared building rubble), on which in turn a surface seal suitable
for building rubble dumps is applied. In addition, the dump surface
thus formed can also be enriched with excavated soil (dump class 1)
between the mineral seal for the building rubble dump and the layer
of cultivatable soil.
In the Illustrative Example according to FIG. 2, a special wastes
dump 2 is covered with a water-removal and/or gas drainage layer 8
and additionally provided with a mineral sealing layer 9 having a
permeability K.sub.f of .ltoreq.5.times.10.sup.-10 m/s. A building
rubble layer 5 several meters thick is then deposited thereon, the
said layer also serving as a root barrier. The building rubble
layer 5 is then followed by a mineral sealing layer 10 having a
permeability K.sub.f of .ltoreq.10.sup.-8 m/s and, on top of this,
a drainage layer 8. Finally, soil 6 capable of being penetrated by
roots is then applied to the multilayer dump, as an uppermost
layer.
The multi-layer dumps described and shown in FIG. 1 and 2 can be
provided, in accordance with FIG. 3, with a channel system for
removing and controlling surface water which seeps in. Drainage
pipes 11 having connections in the individual dump layers are laid
for this purpose, the said drainage pipes leading to control shafts
12. Regardless of the analytical result, the seepage water is then
fed either to a seepage water channel system or to a rainwater
channel system.
In another well-tried embodiment of the novel disposal process, the
outer dump consisting of building rubble and excavated earth 5, 6
and shown in FIG. 4 is composed of three layers. The lower layer 13
consists of drainable building rubble having a thickness of at
least 0.3 m. The second layer 14, which lies on top of this, is at
least 2 m thick and consists of slabs or blocks 15 of a mineral
material resembling building rubble and/or excavated earth
compressed under high pressure, which are laid to overlap in the
manner of roofing tiles (as in FIG. 4) or like building blocks, in
a layer thickness of at least 0.2 m, on the bed 13 of drainable
building rubble. The compressed layer 14 of blocks has particularly
high mechanical strength. A layer 13 of drainable building rubble
is in turn deposited as a third layer on the layer 14 of blocks.
The said layer 13 is finally provided with the surface-sealing
system comprising the sequences of layers 6, 8 and 10, which system
is prescribed for building rubble dumps and is illustrated in FIG.
3.
* * * * *